It’s never easy selecting the year’s top 10 events in the world of astronomy but we’ve done our best! Read on for a selection of some of our favourite events of 2017.

1. Cassini Ended a 20-year Mission

Launched in 1997, Cassini was a joint project between NASA, ESA and the Italian Space Agency. The spacecraft entered Saturn’s orbit in 2004 and spent 13 years orbiting the gas giant and its moons, resulting in incredible discoveries and close-up images. One of these discoveries was that Titan, a Saturn moon, appears to have a landscape strongly resembling that of Earth with clouds, rain, lakes and mountain features!

In April 2017, the spacecraft began a series of 22 deep dives between Saturn and its rings, edging closer each time and gathering more data to be sent back to Earth in its final days. On September 15, the craft began its final descent and plunged into Saturn’s atmosphere, burning up as it encountered the resistance.

On August 21, a total solar eclipse occurred, passing from the East to West coasts of the USA. The entire country was in on the action, with at least a partial solar eclipse visible across all mainland states while the path of totality stretched from Oregon to South Carolina. The last total eclipse visible in the United States was in 1979, making this a momentous occasion for many.

A solar eclipse occurs when the Moon passes between the paths of Earth and the Sun, blocking the Sun’s light from reaching Earth and putting a shadow on whole cities. A partial eclipse occurs when only some of the Sun’s light is obscured, whereas a total eclipse occurs when the Sun is completely obscured, causing complete darkness during daylight hours.

For those who missed out, fear not, the next total solar eclipse will occur on July 2, 2019, and will be visible across parts of Argentina and Chile.

To learn more about the 2017 eclipse check out our blog post on the event.

Short Gamma-Ray bursts have been detected in the past and were theorised to have emerged from the collision of neutron stars but this was the first time it was confirmed. Richard O’Shaughnessy, a scientist with the LIGO project, describe this detection event as “a transformation in the way that we’re going to do astronomy.”

4. Out of our Solar System

In October 2017, it was announced the first known object from another galaxy, 1I/2017 U1 reached our galaxy. The name ‘Oumuamua’ was chosen by the team from the Pan-STARRS observatory who were the first to discover the small asteroid. A Hawaiian name meaning “a messenger from afar arriving first”, it is a fitting title for the interstellar object.

The object was found to have an unexpected shape, looking like a thin barrel or ‘cigar’. Travelling at speeds of 95,000km per hour, the asteroid was around 0.4 km long and likely a dark red colour. Unlike other asteroids in our Solar System, Oumuamua is not gravitationally bound; that is, it has not been captured by our Sun’s gravity and will return to interstellar space following its journey through our Solar System.

5. Asteroid flyby

Earlier this year, NASA announced a test of their planetary defence systems with the asteroid, 2012 TC4, as it safely flew by Earth on October 12. Although relatively close, there was still a significant distance of 42,000 km between Earth and 2012 TC4. The asteroid, estimated at 10 to 15 meters in diameter, was of interest to NASA’s tracking and detection network as they calculated 2012 TC4’s trajectory as it passed by Earth. Continued observations were undertaken by NASA and other astronomers, which included those within the International Asteroid Warning Network who treated the event as a worldwide training exercise.

Read more about NASA’s asteroid missions over 2017 in our blog post here.

6. Rocket lab launch

On May 25, 2017, Rocket Lab, the US aerospace corporation with a New Zealand subsidiary, launched its Electron test program. The rocket, named ‘It’s a Test’ was the first orbital class rocket to be launched from a private site. Taking off from Mahia Peninsula, on the east coast of New Zealand’s North Island, Electron was designed to allow for the launch of small satellites to low Earth orbit at an increased frequency on a commercial basis.

The second test rocket ‘Still Testing’ was prepared for launch during a ten-day launch window in December 2017 but due to faults the launch failed to occur within the launch window and was postponed to 2018.

7. Sputnik 60th anniversary

Sputnik 1 was the first artificial Earth satellite. Launched on October 4, 1957, Sputnik celebrated its 60th anniversary in October 2017. The Soviet Union successfully launched the satellite, beating the United States in a race to put the first object into orbit.

The radio signal onboard was detectable even to radio amateurs and the flight path covered virtually the whole of Earth. Sputnik burned up upon re-entering Earth’s atmosphere on January 4, 1958. The success of the satellite triggered the Space Race and the competitiveness of the Soviet and American sides led to numerous advances in technology and advancement across all scientific fields.

8. 40 Years since Uranus’ Rings Discovered

In 1977, James L. Elliott, Edward W. Dunham and Jessica Mink discovered the rings of Uranus. They noticed that a star’s brightness dropped sharply before approaching Uranus and reappearing shortly before the planet, indicating the presence of something which was blocking out the light. What was originally supposed to be a study on the atmosphere of Uranus, resulted in the confirmation of Uranus’ rings.

The rings were first theorised in 1782 by William Herschel but confirmed by Elliott, Dunham and Mink over 100 years later. This year marked the 60th anniversary of this event and is a reminder of how far our knowledge of Space has come in such a relatively short amount of time.

9. Solar System Twin

Until recently we were the only known Solar System to have eight or more planets orbiting a single star. On December 14, NASA announced in a press conference that their Kepler telescope, along with help from Google’s artificial intelligence, had discovered another two planets orbiting the star Kepler-90, 2,545 light-years away from Earth.

Unfortunately, the planetary system is unlikely to hold the key to life beyond Earth. Planets orbiting Kepler-90 are much closer than we are to our own star; it’s outermost planet, Kepler-90h, orbits at the same distance as between Earth and our own Sun. This creates temperatures which are believed to exceed 400 degrees Celsius on at least one planet – a temperature too hot for the likelihood of life to be high.

10. Space Station Records!

It was a busy year on the International Space Station. In 2017, Peggy Whitson broke the records for total time spent in space by an American, the oldest women in Space and most total spacewalks by a woman!

Images at top: Cassini program manager at JPL, Earl Maize, left, and spacecraft operations team manager for the Cassini mission at Saturn, Julie Webster embrace after the Cassini spacecraft plunged into Saturn (NASA/Joel Kowsky); The total solar eclipse is seen above Madras, Oregon. (NASA/Aubrey Gemignani)

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